Rock drills



P. H. NAST ROCK DRILLS July 26, 1960 5 Sheets-Sheet 1 Filed sept. 1, 1555 w. m m m mm EN PMN N r. @TQ Q Ufj j l w .SM l ...AMHA

L WHNNI P. H. NAST ROCKDRILLS July 26, 1960 3 Sheets-Sheet 3 Filed Sept. l, 1955 I l l I 1 l Pl @u A Q wr. ,/@N

UM "h f f a INVENTOR. 1 ff. nu(

j @wk ROCK DRILLS Paul H. Nast, 1632 Highbrdge Road, Cuyahoga Falls, Ohio Filed Sept. 1, 1955, Ser. No. 532,055

4 Claims. (Cl. 121-15) This invention relates to new and useful improvements in rock drills, more particularly drills employed with rotary drilling equipment to which the drills are attached for rotary motion, and it is among the objects thereof to provide a rock drill in which the drill bit is actuated by a fluid pressure acting upon piston hammers which may be ernployed in multiples in axially joined cylinders and in which the piston hammers may be operated as individual units in synchronism or as integrally joined members.

Another object of the invention is the provision of a rock drill of the rotary type of the above designated character in the form of a simple, compact unit that is adapted to be submerged in the hole which it drills and in which the pressure tluid employed for actuating the piston hammers is ported through the bit and/r cylinder walls for blowing out the rock cuttings.

it is still a further object of the invention to provide a rock drill employing multiple piston hammers utilizing a composite housing structure that includes the back head, the piston cylinders, a chuck housing and a housing cover joined by rods, the said enumerated parts being readily machinable prior to their assembly as a drill unit.

It is still a further object of the invention to provide a piston operated rock drill in which the air pressure to opposite sides of the piston heads is controlled by a single valve and in which the separate piston hammers are synchronized in their reciprocatory movement by means of a pressure differential maintained on the front and rear sides of the piston to render them movable simultaneously.

These and other objects of the invention will become more apparent from a consideration of the accompanying drawings, constituting a part hereof, in which like referdrawings, in the chuck housing cover 11 and extend through the described parts and are fastened by nuts 15 at the threaded end 16 of the rods 12, as shown in Fig. 1.

Disposed in the cylinders 3, 4 and 5 are piston hammers having stems 17, 18 and 19 having heads 20, 21 and 22, respectively, the piston heads being slidably mounted for reciprocatory movementin the cylinders 3, 4 and 5. The piston stems 17, 18 and 19 are of graduated diameter, stem 17 being larger than stem 1S which latter, in turn, is larger than the stem 19 and with the piston heads 20, 21 and 22 all of the same size, the difference in the diameter of the stems 17, 18 and 19 efects a corresponding diierence in the area of the piston head with which they connect. That is to say, the front area of piston 20 to which stem 17 connects is smaller than the corresponding areas of pistons 21 and 22, the area of piston 22 being the smaller. This effects a pressure ditlerential between the respective pistons useful in a manner to be hereinafter explained.

The drill bit, designated by the reference numeral 23, is provided with the customary cutting teeth 24 and a shank portion 25 that is slidingly mounted in the cover.

11 of the chuck housing lil. The end of the bit shank 25 is threaded, as shown at 26, the threaded portion interacting With the thread of a spline nut 27, also shown in Fig. 15 of the drawings, which is free to reciprocate in slots or grooves 2S provided in the chuck housing 1t) without revolving except with the drill housing. The bit 23 is assembled bysimply turning it and threading it into the nut 27. As shown in Fig. 4, the respective piston hammers and bit shank are in abutting engagement which is maintained during the operation of the rock drill, as will be hereinafter explained.

Fluid pressure is supplied to actuate the piston elements through the passage 29 in the center of the shank, passage 30 leading to a rvalve chamber 31 that communicates with a drill hole 32, and a passage 33 in the cylinderl front head 6. A disc valve 34 is adapted to abut valve box 6 to seat thereon as shown, or in its other position, to abut the seat 35 in the shank portion 1. The drill hole 32 is connected by a passage 36 with passages 37,'of which there are four, as shown in Figs. 7 through 12, the passages 37 communicating with the cylinder chambers through ports 38. The passage 33, on the other side of the valve 34, is connected by the passage 39 with --fluid pressure passages 40, of which there are four, as

shown in Figs. 9 through l2 of the drawings, the latter being connected by ports 41 and 41a in the cylinder heads 7 and 8. The chuck housing stem 9 is provided with four passages 45 that register with grooves 46, Figures 4, 13 and 14 leading to a center hole 47 that extends to the end of the drill bit 23. Cylinders 3, 4 and 5 are provided with 'exhaust ports 42, Fig. 4, located in exhaust grooves 43 that are also shown in Fig. 10 which are conthe lines 5-5 through 17-17, shown in Fig. 4 of the drawings;

` Fig. 18 is a side necting bolt; and

Figure 19 is a cross-sectional view, partially in elevation, corresponding to the view of Figure 4, but showing the piston stems 17, 1S and 19 of diierent diameters.

With reference to Fig. 4 of the drawings, the numeral 1 designates a back head or what may be termed the shank of the drill unit having a threaded portion 2 for engageelevational view of a tie rod or conment with a rotary drill pipe, not shown. A plurality of Y having square heads 13 that lit in slots 14, Fig. 16 of thev nected by passages 44 with the passages 45, as shown in Fig. 13, to direct the exhaust expandingpressure iluid `from cylinders 3, 4 and 5 to the center hole 47 to blast -the cuttings from the end of the drill bit 23 to the surface end to prevent their plugging the space between the drill bit and the cover 11.

The operation of the above-described rock drill mechanism is brieiiy as follows:

With the valve 34 abutting the valve box 6, as shown Yin Fig. 4 of the drawings, air supplied through the passage 29 passes into the valve chamber 31 and to the lefthand side of the disc 34, as viewed in Fig. 4,to

ment of the pistons toward the left, as viewed in the drawings. As the piston heads cover the exhaust grooves 43, the air between the piston heads and cylinder heads will. be compressed as the pistons move rearward until Patented July 26, 1960y .port passages, 40 and. act upon thepistonhadssmuls slyrpriossuro boina oquhlihaliofthe oylndorfohamhei-s. ',lhepistomhammers will. t hen,-continue togtr vel towardthe right or forward end. to act uppnkthe .tilg ,stem. ZSto impart an impact, ,blow.,.on the ..g1 1 tti ng fayept thebit .Becausegthe,headyo` piston :.20 .is en- .tirely exposed A due to -,the.absence .of thepistonsterns ,act uponT theA .heads 21 and- 22, greatergforceiwilhbe T ,,asser,t ed.'by the pistont 20, which causesgit togmaintain c ntact with the .head 21 and through the pistorrstem 518 -witl1 the,head 22 ofthe end, piston.

.- Upon.return movement, the compression force incylinder,V 5 on the e forward or. .right hand end @of `piston 2 2 will likewise assert an impulse to:.startmouement of the pistons toward the left.end, andwhen the-ports 38 f ,aref; exposed by the pistonheads intheirfrearward. move- A rrirnthe, force ofthe compressedduidn thefrespective '..Ieyiihdersesopihs through tho nortSS-wiil .cause the .sralye disc.f34; to. snap over yto seatonfyalye-lbmox, 6 clos- :ing gassoso-13- Tho PIoSSUro-.HUidWILthohnaseizom ptfheralveohahiher lthroheh Passages. 3.2,. 36 .andinio ,.,theports 38 to acceleratemovement of the .piston heads f toward the left, as previously explained.

Because of the difference in the sizes Iofthe,pistonsterns 1 7,18 rand 19, the latter being the lsmallest, piston 22, S to ,whichit is connectediwilllhave a .larger ar ea .on the righthand or stem end. than the pistonszl and 2,0,.tl 1 e re by tending to accelerate piston ,22. whichfunctions to Emaintain effective contact of the vpistoirheads, and stems in,their movement to theleft, ,as viewed in.the.drawngs- It is therefore seenzthat the multiple Vpiston hamimersact as an integral unit and could bejntegrallycon- '.nected without altering the operation of the; device.

yltdseviclent from vthe, foregoing deseriptiomotthe I.invention thatthe arrangement of tandem cylinders-rand ,.pistpnhammers in conjunction'withy-a singlepperating valye with the porting of the,tandemlcylindfrsrsas'described, provides a simple, durable rock dr ill ystructure with a simple method of attachingthejdrill; @manner .;topermit hammer motion .without strilringthedrillgbit. .I'his. end motion of the ldrill bit allows forward travel of ,the bit. when it does not bottomin-theholein which it is drilling, `and in `thedrilling operationitgisessential that the drill bit has acertain amount ofiree end motion ..because whenthe piston hammers lstrike; blowsonthe drill bitit must be free tortravel.,forwardtdaHow the cutting edges to penetrateY therock. perrnits the v. forceofvthe blows tobe transmitted ,thrqugh the drill bit tothe cutting .edges where it. is .spentlin the @rocks-1 otherwise the Ymachine proper would absorb, the;f g rce of the blows.

.i The. other importantpurpose of the freediqatingphpk ewhen lowering` into or pullingout ofE- theholegasin the .c asewhen removing or adding. drill pipeiengthsto the string, is to have the piston hammersroperating sogas tolset up vibrations in thedrill pipe, I nalringL easier to remove or enter into a holetliatdsi not clear ;of r o ck uttings or .when ,smallroeksor particles^Y @all info? the h ole.` .Naturally it is v not,necessarygand wouldgcause u urmlrn-:a stress on. the machine if the; piston hammers would be strilringblows on the drill bit during this ,parc of;jt he ,drilling cycle. Therefore,.the drillhbit.-moyesiorwardor .anarrfrom the striking point of the pistohihommersiwhen ittisnot held ,down on the rock.

Also, true synchronization byE usenet, diierentialfareas r .otllepiston. hammers is possible -byfthei-porti-ng arrangetglsnttof-.thomhltirlo.piston oylihsierst-.infwhiohgthe pressures equalize because o'r' the fact that air expands equally in all directions and pressure cannot increase or decrease in one cylinder before the others.

The compression force in the rear cylinder by the piston 5 hammer action forces the valve from its seat and actually pushes back the air through the supplyport, causing a pulsation at theendof` each stroke due to the cushion of air that stops and starts piston hammers on reverse action. Theiforwardstroke is similar to rearl'O ward,'exceptihatachblow.uponjhe.drillbit stops the piston hammers ,an A. the.compression force in the front cylinder chamber reverses piston hammer action.

The highfpressure airll entering thetdrill insures high velocity of the ,piston-hammers to strike blows of great force and when exhausted from cylinders will expand and drop in pressure so that a large volume of air is available to blow the rock cuttings from the drilled hole. Althoughone embodiment of the inventionhasbeen hereinillustrated andy described, itwill be eyidenttQthose 20. skilled in the artthat various modiications may be made inthe v details of construction without. departing frgmgthe principles herein set forth.

,.Iclaim: q1.. .In a nhohmatof piston, operated.,.devoe a.; cyihider 25,honsinggdiyidedinto a plurality of cylinderh-chamberlsLa plurality pf piston hammers disposed in `said cylinder ,.ohsmherswithnho .ends-ofthe. pistons in .abilities sesos@- ...Inehtlh reciprocating -member at oneehd, of. said. cylinder.; housings-.adapted.foronshsement .by..,tho .oJ-1d. piston 30...-hah.1mor,-,fthe other. end .of. said.. oylhdenhousihs boing provided-with means 'for positioningthe, nuit in relation vto the. worktobeacted upon, Vsaid means having an air flow passage leading to a supplycf fluid pressure,l and J.saidvcy1irnlerhousing having p orted passages communi- 5c.ating;with .said air ow passage and with the cylinder :chambers onopposite sides of the piston hammers, and va,.'valve flsposed between said pressure source andthe cylinder. ,ported passages. to direct fluidl vpressure from the sourcetgalternately to opposite sides ofthe-piston hammers.

L In afpneumatiopiston operated device, a cylinder housing tdiviled into,a plurality of cylinder chambers, a, plurality pt ,piston hammers .disposedin said cylinder -,chamhers..wi th the ends,of the pistons abutting engagernent, vaf-reciprocating memberatone end of said cylinderghoilsingz'adapted for2 engagement by theend.

piston hammer, l,the other. .end of said cylinder, housing .heilig..provided;with meansfor positioning .theunit in ,relation -tothe,..worl;`torbe acted upon, said. means having an air,owpassageleading to a supply.iofl 1id..pres sure,f;and1 saidy cylnder housing having, ptnted` passages 2.6.9111.I111nicating-.with.said .air ow passage. andi- .with'the cylinder chambers on opposite sides ofthe pistonhammers, and a valve disposedbetween Saidpressuresource and the-,cylindegportedpassagesto direct duid pressure from the source alternately to opposite sides of the `piston hammers,. said. valvebeing operated in its how-controlling movements by the tinide pressure. from thesonrceyand @decompression force ofthe piston hammers. .in their osrsoinrooating ,moremsnt 3. A pneumatic piston operated device as set-forthwin ,claim Lginawhichgthe pistonwhammers consist o lpf heads having shanks extending throught andingsliding v engagerneut;-BJS/ith thegpartitions dividingthe cylinder lh ousginggintcylinder.chambers, the -ends of which-abut ,the hoods-soft.adjacentpistons` the Shanksr of. .adiscentv piston hammers heinge-of-graduated diameters `to. provide lgraduatecl piston. areas` on Athe l shank side- Aof the: piston hamin rs diminishing-in size-Ifrom the working .end to the rig-,end ofthe Yunit, wherebyin,bothdirections-.pof ,reeip eateryf --rrlovemennl of. the` piston; hammers lthe l end restons. aref oa-maximum :areatoaoocierate fthe. piston travelg10i?,gtheA endo` piston f hammers --in -the-A direction; of

f movement.` whereby perfectsynchronism- 1 ofthe piston warhammer moyetrientsis. obtained.

hammers. 2,851,251 Mori Sept. 9, 1958 

